Got a gasoline-powered lawn mower or garden tractor that’s wheezing its way toward the junkyard? You may want to keep it running until you see if Congress passes the Greener Gardens Act.

The bill would give a 25 percent tax credit of up to $1,000 to anyone buying power lawn, garden, or forestry equipment that meets certain “green” requirements.

Qualifying power sources would include electricity and probably also propane, natural gas, biodiesel, ethanol, methanol, compressed natural gas, and even gas-electric hybrids, which, as in hybrid vehicles, team electric motors and batteries with a smaller gasoline engine. These hybrids would likely be seen in large commercial machines, such as golf-course mowers.

To qualify under the proposed legislation, equipment such as a lawn mower or chain saw would have to produce no more than 50 percent of the regulated pollutants it is now allowed to emit under federal standards. That will mean looking for alternatives to gasoline.

“Building early consumer demand for cleaner technologies is a proven way to create a growing market that can harness American ingenuity to create new jobs and reduce our reliance on foreign oil,” says Sen. Patrick Leahy (D) of Vermont, a cosponsor of the bill.

Both environmental groups and outdoor equipmentmakers support the legislation. It will encourage energy independence, promote cleaner air, and drive development of new technologies and new products, says Kris Kiser, executive vice president of the Outdoor Power Equipment Institute, which represents manufacturers. “So I think it might have legs.”

The United States, Senator Leahy says, has some 50 million acres of lawns and other “managed” grass. Cleaning up emissions from the machines that care for it can cut air and water pollution.

The tax credits would be similar to those offered to homeowners who buy energy-saving doors and windows, insulation, or more efficient furnaces.

While a tax credit would give lawn and garden manufacturers an incentive to move more aggressively into alternative-fuel products, Mr. Kiser says, greener equipment is already beginning to emerge. Three companies are bringing out electric riding mowers, which should be able to run about 90 minutes between charges – although that, he concedes, won’t be good enough for some commercial users, who need to have equipment that can operate nonstop all day long.

“Our guys are out there experimenting with a lot of stuff, and we’ll see where the market takes us,” Kiser says.New federal pollution standards for lawn mowers and other small engines have already made them much “greener,” he says. “We’re 95 percent cleaner than we were in 1997.” Still, the Environmental Protection Agency estimates that operating a conventional gasoline-powered lawn mower for one hour releases the same amount of pollution as driving a car for about 20 miles.

A cash-for-lawn-and-garden-clunkers bill isn’t likely to pass on its own, but would be inserted as part of a much larger climate-change or energy bill, Kiser says. Because of its energy-independence and air-quality benefits, “a lot of folks think [the bill] will be dealt with, and sooner than later” – at the earliest in late summer or fall, he says.